Cancer has claimed the life of a former smoker who had a prominent role in a U.S. government anti-smoking campaign that featured graphic ads.

Terrie Hall, 53, died at a hospital in Winston-Salem, N.C. on Monday, the Associated Press reported.

Hall was diagnosed with oral and throat cancer and had her voice box removed years ago. The cancer, which spread to her brain this summer, was caused by the cigarette smoking she began in high school, according to federal Centers for Disease Control and Prevention officials.

"She was a public health hero," said Dr. Tom Frieden, director of the CDC, which conducted the campaign, the AP reported. "She may well have saved more lives than most doctors do."

Hall had a leading role in the "Tips from Former Smokers" campaign, which focused on how smoking-related cancer ravages the body. In her first ad, Hall was shown putting on a wig, inserting false teeth and using a scarf to cover a hole in her throat. It was the campaign's most popular ad and received more than 2.8 million views on YouTube, the AP reported.

Another ad featured Hall speaking with her artificial voice box and advising smokers to make a video of themselves singing or reading out loud. "I wish I had. The only voice my grandson's ever heard is this one," Hall said in the ad.

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Fetal Pain Science Unclear

Since 2010, a dozen U.S. states have enacted laws banning abortion at 20 weeks after conception, saying that fetuses can feel pain at that point of development. However, the science is unclear.

Most scientists who have waded into the debate have said they believe that if fetuses can feel pain, it's not until well after 20 weeks and after the point in time when nearly all abortions occur, The New York Times reported.

Abortion opponents say that some scientific research shows that fetuses can feel pain at 20 weeks after conception. One of those scientists said fetuses could likely feel pain then, but added that the few abortions performed at that point could be done in ways to avoid pain.

He and two other researchers do not believe their work or current evidence provide scientific support for abortion laws based on fetal pain, The Times reported.

In some cases, scientists' opinions have changed as more studies have been conducted. One of those is Dr. Nicholas Fisk, a senior maternal-fetal medicine specialist at Royal Brisbane and Women's Hospital in Australia, and former president of the International Fetal Medicine and Surgery Society.

He once believed that early fetal pain was "a major possibility" after discovering that fetuses receiving blood transfusions showed increased stress hormones and blood flow to the brain, and that painkillers lowered those levels.

However, neurological research has convinced Fisk that fetal pain "is not possible at all" before 24 weeks, The Times reported.

Supporters of fetal-pain abortion laws contend that surgeons' use of anesthesia and painkillers when operating on fetuses in the womb proves that fetuses feel pain. But fetal surgeons say the drugs are used for reasons other than fetal pain.

Anesthesia is given to the mother and fetuses are given muscle relaxants and narcotics, according to Dr. Scott Adzik, a fetal surgeon at Children's Hospital of Philadelphia. The drugs are given to prevent pain in mothers, relax the uterus, immobilize the fetus and block harmful effects of a fetus's hormonal stress response, he explained.

Adzik said he did not know if fetuses would feel pain without these drugs, The Times reported.

Supporters of fetal-pain abortion laws often cite the work of Dr. Kanwaljeet Anand, a professor of pediatrics, anesthesiology and neurobiology at the University of Tennessee's Health Sciences Center.

He believes it likely that fetuses can feel pain at 18 to 24 weeks, but added that the "issue of fetal pain does not have much relevance for abortion, since most abortions are performed before the fetus is capable of experiencing pain," The Times reported.